1.0 Why should I consider honing a cutting tool?
Honing the edge of a cutting tool has several benefits including:
- Improved tool life
- Improved surface finish of the workpiece
- Reduced spindle load
- Reduced overall cost of manufacturing
2.0 What exactly is “honing” or “edge prep”?
MET defines honing as the creation of a controlled radius and a surface finish improvement at the intersection of two points that create the cutting edge. Honed edges can be full radii, waterfall or a reverse waterfall.
3.0 What type of tools benefit from a honed edge?
We validate benefits with all types of tools, from H.S.S. to carbide. The major benefits occur on carbide prior to the coating of a tool. The radius edge allows the coating the adhere better to the tool surface since no dead sharp corners or burrs are present. If not honed prior to coating, the edge can fracture and expose substrate materials, shortening life and effectiveness of the coating and the tool. The surface finish of the edge is also improved, reducing friction and allowing for better chip evacuation. Tools include:
- Drills – all types of points
- End mills – O.D. and face – roughing and finishing
- Carbide inserts – most shapes
- Form ground round tools
- Gear hobs
- Gear shaper cutters
- Spiral bevel stick blades
- Saw blades – round and hack style
- Rock drills
Tools that are not coated can also benefit from the controlled radius applied to the cutting edge by reducing friction and increasing the contact area of the cutting edge to the workpiece, strengthening the tool.
4.0 How does it work, and what can I expect from the process?
Honing is a dry process achieved by applying a nylon abrasive filament brush to the edges of the cutting tool. The brush filaments are constructed from a nylon carrier that is co-extruded with an abrasive grain. This means that as the brush wears, new abrasive grains are constantly being exposed to the workpiece. These flexible brush filaments act as “flexible files”, wrapping and wiping across all edges evenly. There are two separate dynamics to using these brushes, one being the cut that the abrasive creates, the other being the force of the filaments as they contact the surface. Many factors determine the end result, such as speed, direction, cycle time, depth of engagement, centerline placement, etc. These settings can be pre-determined and maintained using any MET machine to create a honed edge.
The nylon abrasive brushes can be made in several different configurations. Some of the factors include:
- Filaments – The filaments can be round or rectangular, straight or crimped, and are available in many different diameters depending on the application.
- Abrasive grains – The abrasive used in the brush can also vary greatly depending on the application, some abrasives that are used are silicon carbide, aluminum oxide, ceramic, and diamond.
Depending on the hone that is desired, a brush configuration is typically available to allow that specific end result to be created.
When an edge is sharpened, the post ground material will create a ragged edge as the grinding wheel exits the cutting edge. This happens because there is no force pushing back on the edge to shear the burr away. If this edge is not addressed, the tool will have a dead sharp cutting edge that will quickly wear and fracture.
5.0 How much control and consistency can I expect?
Once a process is defined, it can be controlled to within .0001″ from part to part. The MET machine uses multiple programs to allow standard cycles to be used to achieve properly honed edges. By saving these “recipes”, the process can be repeated quickly and easily with minimal effort from an operator.
6.0 How is the edge measured and validated?
The edge can be measured in a few different ways. Some common methods include visual measurements under a microscope, or the use of a contour tracing. There is also image analysis software available for inspection, allowing the user to measure in 2-D and 3-D.
The contour tracing method shows the exact size and shape of the radius. It allows for better accountability to slight changes made in the development of the honed edge. Contour tracing is a part-contact measuring method, which can have potential disadvantages for some tools.
7.0 How do I know what hone my tools need?
The range of hones is as large as the range of tools. As a rule, the harder the workpiece material, the larger the hone required. The use of waterfall and reverse waterfall radii is for more specific end results. The best way to perfect the honed edge of a tool is to test the results and make adjustments accordingly, as each application is different.
8.0 How can I get my tools honed, and how much does it cost?
MET offers a honing service for all tools listed above. Contact us with your application today.
Mutschler Edge Technologies also offers several machines for sale. We will gladly show you the process and explain the machine before you purchase it. Leasing is available upon request. Please contact us and tell us about your application.